Kevlar and mats and such, oh my

mshelton · Post by **mshelton** » Wed Apr 18, 2007 6:13 pm

It's project time, I have an old Zealot, that's in decent shape, in my garage that I'm going to finally start working on.

The boat has a few small cracks and one spot that took a med sized blow that has slight delamination. I sanded all of these spots down to patch them with some S-glass but then thought about it and I'm going to sand the entire bottom, patch the few spots that could use it and cover the whole thing in a sheet of kevlar. Yes I know it'll make the boat much heavier than it was intended but I want a paddleable boat for locally here on the James, I'm going kevlar because of the cheezegrater rocks we have here. I'll probably put a new layer of S-glass on the top too with some retarted graphic / paintjob as to maintain a level of stupidity that I prefer.

My question is, what's a good thickness of kevlar to use, I checked out Sweets composites but am kinda clueless. It doesn't have to be some bulletproof crazy heavy layer, just enough to make it serviceable. Also I've only used West Systems epoxy for everything I've worked on in the past and I'll probably use that for the hull but the problem is that it turns yellowish. What can I use for the deck that has a chance of staying clear, I want my retarded graphics / paint job to look sharp! I tried vinylester and MEK-P once for about 10 min and quickly swore it off as the juice of the devil himself. Anything else out there that would work?

msims · Post by **msims** » Wed Apr 18, 2007 7:02 pm

I think east systems does better than west, in terms of not yellowing. I've used east for a wood stripper, it works just as well.

Mike.

mshelton · Post by **mshelton** » Wed Apr 18, 2007 8:35 pm

East System, they sell that stuff in the states?

Bob P · Post by **Bob P** » Wed Apr 18, 2007 9:43 pm

A Google search turned up this for East Systems.

You realize that Kevlar is yellow, right?

You'll never see the color of the epoxy.

Frankly, Kevlar is a poor way to patch the outside of the hull. It's compressive strength is lower than S glass and you can't sand it without major fuzzing.

Sweet Composites has spec's on thicknesses. I would use a 4-6 oz glass to cover an entire boat (after doing the local patches) myself.

msims · Post by **msims** » Wed Apr 18, 2007 10:36 pm

you can try bearmountainboats.com forums. There are hundreds of boatbuilders - mind you most of them are glass, and they might not fully understand what you're trying to acheive..

"you want to what with a what??"

But you may find a few folks that have built their cedar strip canoes out of kevlar?

Mike.

John Coraor · Post by **John Coraor** » Thu Apr 19, 2007 1:19 pm

I want to second what Bob P said - you would probably be better off using S-glass, or even regular E-glass, than kevlar on the outside. Because it is poor in compression but has great tensile strength, kevlar is best used as the inside layer of a layup. Also, as Bob noted, kevlar will indeed hide whatever is underneath, whereas you have some hope of seeing through a glass layer, although as thickness increases whatever lies underneath will appear cloudier and more "soft focus."

I haven't had a problem with West Systems epoxy yellowing, but vinylester is another option. It is not quite as strong as epoxy, however, and if the original boat is an epoxy layup, you should probably use epoxy for your repair.

John

Post by **sbroam** » Thu Apr 19, 2007 1:42 pm

I would suggest an alternative system - composite concrete construction. Concrete is excellent in compression and will continue to strengthen over time and water is an important ingredient in the curing process. Steel, in the form of a welded wire mesh should give you adequate tensile strength. However, if you are creeking, you may need an engineered mat of rebar, however, #3 bar at 6" OC should be adequate. In a lighter weight race boat, a fiber reinforcement may be appropriate. If you are concerned about yellowing - concrete is an excellent alternative. Witness the earliest concrete use by the Romans - it is as white as the day it was poured!

mshelton · Post by **mshelton** » Mon Apr 23, 2007 2:59 pm

Thanks guys,

I've settled on elephant dung and trout semen as an activator.

Now I just need to find a good adhesive for that mix....

philcanoe · Post by **philcanoe** » Tue Apr 24, 2007 2:55 pm

if you are sold on on West Systems, check out their complete product line...they have a clear laminating resin, made for glass-to-glass construction,this will not yellow... yellowing can be greatly influenced by the type hardener and it's age...

IF U ONLY HAVE THE WEST 105 STANDBY this is especially formulated for wood, that's it's big draw and the reason for it's popularity (strippers, sailboats, etc)...great for patch, very poor for entire layer...once had a race, needed boat, had free weekend, and extra west; so new boat...BAD MOVE....cracked very badly, did yellow, and
was a waste of good kevlar, s-glass, and gravlar.

Kevlar on bottom !!! outside layer !!! (even if covered by with layer of something!!!)...I'd read all you can B4 doing !!!!!!

mshelton · Post by **mshelton** » Tue Apr 24, 2007 3:07 pm

The kevlar on the bottom is just for protection against abrasion, I did the highpoints on my Bigboy with kevlar and it's helped a ton with the rocks here in Richmond.

I checked out the product line for West systems, they have a hardener that says it's "exceptionally clear" then in the next sentence "Cures to a light amber color" so yeah....nice product description.

I'll probably just throw some pigment in the top layer then paint it, take it out, then wrap it around a rock doing something stupid.

phreon · Post by **phreon** » Tue Apr 24, 2007 4:39 pm

For pure abrasion resistance, you might want to consider Dynel or Xynole cloth. Both have a higher abrasion resistance and sheer strength than glass (for equal weight that is. They suck up much more resin than glass) , don't make you itch, can be cut with plain scissors and don't fuzz out like Kevlar. Xynole is sometimes called "poor man's kevlar", but is not good for stiffening...it gives too much. An S-Glass/Xynole layup might be a good solution in your case.

Phreon

philcanoe · Post by **philcanoe** » Tue Apr 24, 2007 6:22 pm

hey mshelton,

they have one resin system (not just hardener) that's really clear...used it once on a wood stripper, it was clear, unlike the slight amber color of my previous strippers... however, it might be for wood, and not a true laminating resin

kevlar is really high in tensil strength, so it usually reserved for more inward layers... it's compressive strength is really-really low, so it's not as desirable on the outside...it's modulus of elasticity (may of stated that wrong-just top of head) is what makes it good for impact... it does fuzz bad... you might get more bang for the buck, by using S-glass... if just patching, it wouldn't matter - but I thought you wanted to do the whole

mshelton · Post by **mshelton** » Tue Apr 24, 2007 6:29 pm

I think I'll check out Dynel or Xynole cloth since they seem cheaper, structurally the boat is good but it's a slololololm boat so it's thin and light. Just adding the padding so I can beat it up a little, plus piss off all the "light and fast zomg" folks.

phreon · Post by **phreon** » Wed Apr 25, 2007 3:38 am

mshelton wrote:I think I'll check out Dynel or Xynole cloth since they seem cheaper, structurally the boat is good but it's a slololololm boat so it's thin and light. Just adding the padding so I can beat it up a little, plus piss off all the "light and fast zomg" folks.

How much Xynole do you forsee needing? I managed to over order and will likely have plenty left over.

Phreon

mshelton · Post by **mshelton** » Wed Apr 25, 2007 2:15 pm

I plan on covering the whole hull of the boat, so I'd probably need a good bit, maybe 20 square feet.

C-Forum

Kevlar and mats and such, oh my

Kevlar and mats and such, oh my

Abrasion resistance